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Ask the Expert: Treating brain tumors

Special for The Republic | azcentral.com
Published 3:53 p.m. MT May 22, 2015

Answer: Unlike most other cancers, tumors in the brain — such as glioblastoma — are especially difficult to treat because of three key reasons.

One of the major difficulties is finding drugs that can penetrate the blood-brain barrier, which buffers the brain from the rest of the body's blood-circulatory system.

Located along capillaries, the blood-brain barrier protects the brain from rapid changes in the body's metabolic conditions and minimizes exposure to molecules that are toxic to neurons in the brain.

Another major challenge in treating glioblastoma is its intrusive penetration into adjoining tissues, which prevents the complete surgical removal of the tumors from the brain, even with follow-up radiation and chemotherapy.

It is this invasive, infiltrative disease component that is the ultimate cause of recurrence, resistance and death.

And, these tumors have a propensity to mutate to the point that even within a single tumor there can be multiple genomic signatures.

A TGen-led study, funded by The Ben & Catherine Ivy Foundation of Scottsdale, published recently in the Oxford University Press journal Neuro-Oncology, provides a guide to how these brain tumors might be better treated in the future.

The study, "Towards Precision Medicine in Glioblastoma: The Promise and The Challenges," presents the hope for better treatments by harnessing the power of the human genome.

The study also describes a clinical trial underway for 15 patients at UC San Francisco, guided by TGen research, in which an individual patient's genomic profile is used to offer treatment recommendations to an expert, multidisciplinary panel.

This study outlines strategies for overcoming past failures, primarily by applying targeted combination therapies that match the tumors' genetic changes with drug compounds that can reach the central nervous system.

In the clinical trial begun at UCSF, multiple biopsies are performed on each patient at the time of surgery in different regions of the brain tumor. That is followed by extensive genome-wide profiling, leading to a selection of drugs that would target the brain cancer and diffuse regions of the lesion that cannot be removed by surgery.

Dr. Sara Byron is a Research Assistant Professor at the Phoenix-based Translational Genomics Research Institute, or TGen, Center for Translational Innovation.